Intensified myeloablative therapy and autologous stem-cell transplantation for patients with AML: single center experience

Chemosensitivity of nonleukemic clonogenic precursors in AML patients in complete remission: association with CD34(+) mobilization and with disease-free survival

A high number of CD34(+) cells in the peripheral blood during mobilization in patients with acute myeloid leukemia (AML) in complete remission (CR) is associated with a high relapse rate. The variability in chemoresistance of normal bone marrow precursors has been hypothesized as explanation for the variable CD34 mobilization in AML. In 37 patients with AML in CR, we determined the chemosensitivity of bone marrow clonogenic precursors to maphosphamide and etoposide, which was then correlated with the degree of CD34(+) mobilization. In an enlarged set of 49 patients, we also studied the importance of chemosensitivity of marrow precursors for disease-free survival and relapse incidence. Significant correlations were demonstrated between the peak number of CD34(+) cells and residual growth of colony-forming unit granulocyte-macrophage (CFU-GM) after maphosphamide (R = 0.550; p = 0.0003) and after etoposide (R = 0.793; p = 0.0003). It was possible to identify three groups of AML patients based on chemosensitivity. The mean CD34(+) peak was 33 × 10(6)/L in the hyperchemosensitive group, 141 × 10(6)/L in the normochemosensitive (p = 0.03), and 379 × 10(6)/L in the chemoresistant group (p = 0.002). Failed CD34(+) mobilization was observed in 72% of the hyperchemosensitive group, 23% of the normochemosensitive group, and 0% of the chemoresistant group (p = 0.001). Hyperchemosensitivity of CFU-GM, together with a low platelet count, were independent factors important in the failure of CD34(+) cell mobilization. A disease-free survival significantly inferior to that of all other patients was associated with chemoresistance of CFU-GM (log rank, p = 0.030) and with chemoresistance of burst-forming unit erythroid (BFU-E) (log rank, p = 0.033). Chemoresistance of CFU-GM (p = 0.048) and BFU-E (p = 0.017) was also associated with increase relapse incidence. Nonleukemic nature of these precursors was demonstrated studying minimal residual disease from single colony cells. In conclusion, we found that hyperchemosensitivity of normal nonleukemic CFU-GM is associated with a high risk of CD34(+) cell mobilization failure, while a chemoresistant pattern in CFU-GM and BFU-E is associated with poor disease-free survival and increased cumulative incidence of relapse.

Marrow irradiation with high-dose 153Samarium-EDTMP followed by chemotherapy and hematopoietic stem cell infusion for acute myelogenous leukemia

In four patients, aged 15 - 20 years, with high-risk acute myeloid leukemia (AML), high-dose samarium 153-labelled ethylenediaminetetramethylenephosphonate (153Sm-EDTMP) was used for targeted marrow irradiation before preparative chemotherapy conditioning regimens and allogeneic (three patients) or autologous (one patient) hematopoietic stem cell transplantation. The dose of 153Sm-EDTMP was 703 MBq/kg (n = 1) or 1110 MBq/kg (n = 3). No side-effects occurred during the 30-min infusion of 153Sm-EDTMP. Samarium - melphalan regimens were given to three patients; one had 153Sm-EDTMP - busulfan + cyclophosphamide. Total body radioactivity was below the 133 MBq safe limit before infusion of stem cells (day 14 after 153Sm-EDTMP). No hemorrhagic cystitis, nephrotoxicity or serious infections occurred. Leukocyte engraftment (white blood cell count >0.5 x 10(9)/l) occurred between 12 and 23 days after stem cell infusion (mean of 17 days). Complete cytogenetic and morphologic remission of AML was evident on follow-up marrow aspirate and biopsy specimens from all patients. In two of the four study patients, the disease remains in complete remission and the patients have an excellent quality of life (Eastern Cooperative Oncology Group performance status 0; no medications) and no organ toxicity more than 2 years and more than 4 years, respectively, after their blood and bone marrow transplantations. Thus, in adolescents and adults, 153Sm-EDTMP may provide a relatively simple and effective means for using irradiation to eliminate AML within the marrow.

Increasing dose intensity of anthracycline antibiotics improves outcome in patients with acute myelogenous leukemia

To understand the effect of dose concentration in the overall survival of AML, we conducted a study on the efficacy and toxicity of a drug combination where the dose of daunorubicin was intensified. For this analysis, the outcome of patients entered into two consecutive prospective trials was compared. Inclusion criteria in both arms were identical and consisted of primary AML in adults. Treatment protocol for Cape Town Regimen 4 (CTR-IV) comprised of cytarabine infusion (100 mg/m(2)) and etoposide (100 mg/m(2)), injection daily for 7 days in combination with daunorubicin (45 mg/m(2)) on days 1, 2, and 3. Patients achieving remission were given two further courses of the same chemotherapy and received allogeneic or autologous transplantation. CTR-V was a similar treatment program, except that daunorubicin was escalated on days 1, 2, and 3 to 75 mg/m(2) during induction and to 60 mg/m(2) during a single consolidation. Patients were also offered stem cell transplantation. Between 1990 and 1997, 78 patients (median age 33; range 13-67 years) fulfilled entry criteria and received CTR-IV. From 1998 onwards, 35 patients (median age 36; range 15-66 years) were prospectively enlisted into the CTR-V trial. The patient population in CTR-V had fewer Caucasian individuals (P = 0.02) and had significantly lower presentation hemoglobin (P = 0.0002). Following initiation of induction chemotherapy, 40 patients failed to respond. Among these, 10 patients demised before day 28. Another 30 (25/69 CTR-IV and 5/32 in CTR-V groups; P = 0.01) had leukemia that was resistant to chemotherapy, and all died. Remission was achieved in 59% of patients treated with CTR-IV and 77% of those receiving CTR-V (P = 0.03). CR occurred with a single course in 64% versus 88% (P = 0.02), respectively. There were no differences in the toxicity profile between these two combinations. Disease recurred in 50% and 28% (P = 0.07) of patients. For the 113 individuals, median follow up is 254 (range 19-4,451) and 304 (12-1,702; P = 0.03) days. Survival is 23% and 40%, respectively, favoring patients treated with CTR-V (log rank; P = 0.03). Cox regression analysis showed that treatment group (P < 0.001), FAB type, hemoglobin level, and platelet count were independent factors for response to chemotherapy. Older age and not undergoing myeloablative therapy were the only adverse factors for survival. We conclude that increase in the treatment dose of daunorubicin in patients with AML led to a higher remission rate, particularly with a single course of chemotherapy and had an equivalent toxicity profile. This therapeutic modification is also likely to result in substantial reduction in patient stay in hospital and in the overall expenditure.